Just to clarify...the campaign is already active, and the email has been scheduled to be sent, but the send time has not yet commenced.

Ha ok, scheduled was a poor word choice on my part. In your case, let's say that email 2 is scheduled for 2pm on Wednesday, If I unsubscribe any time before 2pm on Wednesday then I will NOT be sent that 2nd email.

That's weird because I've had to create a separate campaign that would remove someone from a weekly campaign flow when they unsubscribed from the first email sent. I thought that when someone unsubscribes from the first of 5 emails from a drip campaign that they wouldn't receive any of the subsequent emails, but they still did and the emails go out on Fridays.

The Unsubscribed functionality will work even for leads who were in a wait step while they unsubscribed. In other words, leads who unsubscribed while they are in a wait step will not get the next email in the drip.

However, your smart list criteria are not checked again before the second email is sent. This means that if your lead no longer meets the smart list criteria they will still get the second email. For this reason, it is recommended to always have a separate smart campaign in place to remove leads who no longer meet your smart list criteria. For example:

The Unsubscribed functionality is an exception though since this is system managed. Leads who unsubscribe while they are in a wait step will not get the next email in the drip.

It's not so much because it's system-managed... it's the same for any lead field and just depends on when the lead value is checked. Changes take effect on the lead record even if the record is in a wait in a campaign. When the lead comes out of the wait so subsequent steps are executed, they use the then-current state of the lead. That can include removing people from the flow (in the same campaign) based on field values.

Of course, it may be easier to manage this in a separate campaign, and is necessary if that other campaign is responding to events that don't have an equivalent constraint.

Thanks for clarifying . Poor choice of words on my part. What I meant with system managed was that it is automatically checked before the send - even if you don't add a constraint to the second email send. This is not the case for any other lead fields correct?

I usually build a separate smart campaign to remove from flow as there are usually several reasons to remove someone from a flow and constraints don't allow for and/or logic but if not (and if there is an equivalent constraint) I guess you could do it all in one .